#include <stdio.h>  
#include <stdlib.h>  
#include <unistd.h>  
#include <sys/types.h>  
#include <pthread.h>  
#include <assert.h>  

/* 
 * 线程池里所有运行和等待的任务都是一个CThread_worker
 * 由于所有任务都在链表里，所以是一个链表结构
 */
typedef struct worker  
{  
	/*回调函数，任务运行时会调用此函数，注意也可声明成其它形式*/  
	void *(*process) (void *arg);  
	void *arg;/*回调函数的参数*/  
	struct worker *next;    
} CThread_worker;  

/*线程池结构*/  
typedef struct  
{  
	pthread_mutex_t queue_lock;  
    pthread_cond_t queue_ready;

	/*链表结构，线程池中所有等待任务*/  
    CThread_worker *queue_head;

	/*是否销毁线程池*/  
	int shutdown;  
    pthread_t *threadid;
	/*线程池中允许的活动线程数目*/  
    int max_thread_num;
    int run_thread_num;  // 当前活动的任务数
	/*当前等待队列的任务数目*/  
    int cur_queue_size;

} CThread_pool;  


int pool_add_worker (void *(*process) (void *arg), void *arg);  
void *thread_routine (void *arg);  

enum pool_multi_type{
    POOL_WORK  = 0,  // 工作线程池
    POOL_TRUNK = 1,  // 中继线程池
    POOL_NULL  = 2,  // 无效
};

//static CThread_pool *pool = NULL;
static CThread_pool* pool_multi[POOL_NULL] = {NULL, NULL, NULL};   // 多个线程池
static enum pool_multi_type const pthread_arg[POOL_NULL] = {POOL_WORK, POOL_TRUNK, POOL_NULL};
static void __pool_init (int max_thread_num, enum pool_multi_type index)
{  
    CThread_pool *pool = (CThread_pool *) malloc (sizeof (CThread_pool));

	pthread_mutex_init (&(pool->queue_lock), NULL);  
    pthread_cond_init (&(pool->queue_ready), NULL);

	pool->queue_head = NULL;  

	pool->max_thread_num = max_thread_num;  
    pool->run_thread_num = 0;
    pool->cur_queue_size = 0;

	pool->shutdown = 0;  

	pool->threadid = (pthread_t *) malloc (max_thread_num * sizeof (pthread_t));  
	int i = 0;  
	for (i = 0; i < max_thread_num; i++)  
	{   
        pthread_create (&(pool->threadid[i]), NULL, thread_routine, &pthread_arg[index]);
    }
    pool_multi[index] = pool;
}  

void pool_init(int max_thread_num)
{
    __pool_init (max_thread_num, POOL_WORK);
    __pool_init (16, POOL_TRUNK);
}

/*向线程池中加入任务*/  
int __pool_add_worker(void *(*process) (void *arg), void *arg, CThread_pool *const pool)
{  
	/*构造一个新任务*/  
	CThread_worker *newworker = (CThread_worker *) malloc (sizeof (CThread_worker));  
	newworker->process = process;  
	newworker->arg = arg;  
	newworker->next = NULL;/*别忘置空*/  

	pthread_mutex_lock (&(pool->queue_lock));  
	/*将任务加入到等待队列中*/  
	CThread_worker *member = pool->queue_head;  
	if (member != NULL)  
	{  
		while (member->next != NULL)  
			member = member->next;  
		member->next = newworker;  
	}  
	else  
	{  
		pool->queue_head = newworker;  
	}  

	assert (pool->queue_head != NULL);  

	pool->cur_queue_size++;  
	pthread_mutex_unlock (&(pool->queue_lock));  
	/*好了，等待队列中有任务了，唤醒一个等待线程； 
	 *     注意如果所有线程都在忙碌，这句没有任何作用*/  
	pthread_cond_signal (&(pool->queue_ready));  
	return 0;  
}  

/*int pool_add_worker (void *(*process) (void *arg), void *arg, enum pool_multi_type index)
{
    __pool_add_worker(process, arg, pool_multi[index]);
    return 0;
}*/
int pool_add_worker (void *(*process) (void *arg), void *arg)
{
    __pool_add_worker(process, arg, pool_multi[POOL_WORK]);
    return 0;
}
int pool_add_trunk (void *(*process) (void *arg), void *arg)
{
    __pool_add_worker(process, arg, pool_multi[POOL_TRUNK]);
    return 0;
}



/*销毁线程池，等待队列中的任务不会再被执行，但是正在运行的线程会一直 
 * 把任务运行完后再退出*/  
static int __pool_destroy (enum pool_multi_type index)
{  
    CThread_pool *pool = pool_multi[index];
	if (pool->shutdown)  
		return -1;/*防止两次调用*/  
	pool->shutdown = 1;  

	/*唤醒所有等待线程，线程池要销毁了*/  
    pthread_cond_broadcast (&(pool->queue_ready));

	/*阻塞等待线程退出，否则就成僵尸了*/  
	int i;  
	for (i = 0; i < pool->max_thread_num; i++)  
		pthread_join (pool->threadid[i], NULL);  
    free (pool->threadid);

	/*销毁等待队列*/  
	CThread_worker *head = NULL;  
	while (pool->queue_head != NULL)  
	{  
		head = pool->queue_head;  
		pool->queue_head = pool->queue_head->next;  
		free (head);  
    }
	/*条件变量和互斥量也别忘了销毁*/  
	pthread_mutex_destroy(&(pool->queue_lock));  
    pthread_cond_destroy(&(pool->queue_ready));

	free (pool);  
	/*销毁后指针置空是个好习惯*/  
	pool=NULL;  
	return 0;  
}  
int pool_destroy (void)
{
    __pool_destroy (POOL_WORK);
    __pool_destroy (POOL_TRUNK);
    return 0;
}

static int wait_thread_num=0;  // 当前等待任务数
int get_wait_thread_num(void)
{
    int num=0;
    CThread_pool *const pool = pool_multi[POOL_WORK];
    pthread_mutex_lock (&(pool->queue_lock));
    num = wait_thread_num;
    pthread_mutex_unlock (&(pool->queue_lock));
    return num;
}

//static void* __thread_routine (void *arg)
static void __thread_routine (CThread_pool *const pool)
{  
	printf ("starting thread 0x%x\n", pthread_self ());  
	while (1)  
	{  
		pthread_mutex_lock (&(pool->queue_lock));  
		/*如果等待队列为0并且不销毁线程池，则处于阻塞状态; 注意 
		 *         pthread_cond_wait是一个原子操作，等待前会解锁，唤醒后会加锁*/  
		while (pool->cur_queue_size == 0 && !pool->shutdown)  
		{  
            if(pool->run_thread_num>0) pool->run_thread_num--;
			printf ("thread 0x%x is waiting\n", pthread_self ());  
			pthread_cond_wait (&(pool->queue_ready), &(pool->queue_lock));  
		}  

		/*线程池要销毁了*/  
		if (pool->shutdown)  
		{  
			/*遇到break,continue,return等跳转语句，千万不要忘记先解锁*/  
			pthread_mutex_unlock (&(pool->queue_lock));  
			printf ("thread 0x%x will exit\n", pthread_self ());  
			pthread_exit (NULL);  
		}  

		printf ("thread 0x%x is starting to work\n", pthread_self ());  

		/*assert是调试的好帮手*/  
		assert (pool->cur_queue_size != 0);  
		assert (pool->queue_head != NULL);  

		/*等待队列长度减去1，并取出链表中的头元素*/  
		pool->cur_queue_size--;  
		CThread_worker *worker = pool->queue_head;  
        pool->queue_head = worker->next;
        pool->run_thread_num++;
        wait_thread_num = pool->max_thread_num-pool->run_thread_num;
		pthread_mutex_unlock (&(pool->queue_lock));  

		/*调用回调函数，执行任务*/  
		(*(worker->process)) (worker->arg);  
		free (worker);  
		worker = NULL;  
	}  
	/*这一句应该是不可达的*/  
	pthread_exit (NULL);  
}
void* thread_routine (void *arg)
{
    enum pool_multi_type *type = (enum pool_multi_type*)arg;
    __thread_routine (pool_multi[*type]);
    return  NULL; /*这一句应该是不可达的*/
}

#if 0
/*    下面是测试代码  */
void * myprocess (void *arg)  
{  
	printf ("threadid is 0x%x, working on task %d\n", pthread_self (),*(int *) arg);  
	sleep (1);/*休息一秒，延长任务的执行时间*/  
	return NULL;  
}  

int main (int argc, char **argv)  
{  
	pool_init (3);/*线程池中最多三个活动线程*/  

	/*连续向池中投入10个任务*/  
	int *workingnum = (int *) malloc (sizeof (int) * 10);  
	int i;  
	for (i = 0; i < 10; i++)  
	{  
		workingnum[i] = i;  
		pool_add_worker (myprocess, &workingnum[i]);  
	}  
	/*等待所有任务完成*/  
	sleep (5);  
	/*销毁线程池*/  
	pool_destroy ();  

	free (workingnum);  
	return 0;  
}
#endif













